DACS General Meeting
August 2008
Program Review:
What you Always Wanted to Know about HDTV, but May be Afraid to Ask

by Patrick Libert

The title says it all…. I consider myself to be knowledgeable in many technical areas but not this one. Given the fact that my 13 year old 27” Panasonic will certainly want to be buried locally, I have to know what and how to purchase my first HDTV.

Enter Mark Weiss, our presenter at the August General Meeting, as the guru on the often murky subject of High Definition Television (HDTV).

Mark’s organized and captivating presentation was just what I needed.

Mark began mentioning the misconception that if we have an HDTV, it will automatically give us high definition(HD). That is true, if the source we receive is in HD and if the connections to the set handle HD. Presently, we can receive signals on the air, by cable, from a satellite or from the Internet. Interestingly, satellite TV was an early HD provider, before cable companies began their coverage. Effective February 17, 2009, most on-the-air broadcasters must convert their signals from analog to digital. This does not necessarily mean that the digital signal will be in High Definition which requires a substantial investment by the broadcaster.

Some of the most interesting points were:

1. Display distance versus screen size - to see the most details on an HDTV screen, at ten to fifteen feet from the screen a 47” set would be ideal. The higher the resolution, the closer one should be to the set. The higher the resolution, the larger the screen should be.
2. What resolution should we look for? - we should look for a set that produces1080p(pixels vertically) since the HD broadcasts are in that resolution. Choosing a set that handles only 720p will filter out some of the details in the 1080p signal.
3. Aspect Ratio - Most of the traditional TV sets use an aspect ratio of 4:3. HDTV sets, on the other hand, use a 16:9 aspect ratio, i.e., a greater width than height of the screen. As an example, if we are converting from a traditional 27” TV screen to an HDTV and we want to keep the same height of the image, we would have to choose a 32” HDTV.
4. Pros and Cons of the different technologies -
• LCD (Liquid Crystal Display) - Uses less energy, generates less heat, brighter, no burn-in, but has less contrast.
• PLASMA - Has better contrast, wider viewing angle, faster response time, uses more energy and generates more heat, can have image burn-in.
• DLP - used primarily for projectors on very large screens
• O-LED (Organic Light Emitting Diode) - It is still in the development stage but it could be the future of HDTV. Since it does not need backlighting, it consumes much less power than the previous technologies.
5. Connections - From best to worse:
• HDMI cables - carries the full digital signal
• Component Video Cables - carries an analog signal
• S-Video Cables - Carries only a picture signal, no sound.
• Composite (RCA) Cables - carry analog sound/video
Consequently, if we want to transmit the best signal to our HDTV, it is best to use HDMI cables.
6. Deep Color - Some sets will mention that they have “deep color.” This refers to having a color bit depth between 30 and 48 in the display which assures a smooth color transition in certain types of pictures, such as a sunset shot.
7. DVD as a source - One should use an HDMI connection and have a DVD player with 1080p upscaling capability. The DVD player should also be set at the same output as the HDTV, i.e., 1080p on the HDTV will need 1080p set up on the DVD Player.
8. Calibration - One should not assume that the set has been properly calibrated at the factory. You should use a calibration DVD which is sometimes included with certain DVD movies such as those from Disney or with a THX encoding. I see on Amazon.com that this can be bought for just over $25.

There were many other fascinating points mentioned by Mark which made his presentation captivating. Questions from the audience led to his giving us even more information on a topic that will eventually relate to all of us.